1. Field of the Invention
The present invention relates to the use of succinate dehydrogenase inhibitors for controlling powdery mildew primary infections in crops and to a method for controlling those primary infections.
2. Description of Related Art
Powdery mildew is a fungal disease that affects a wide range of plants. Powdery mildew diseases are caused by many different species of fungi in the order Erysiphales. It is one of the easier diseases to spot, as its symptoms are quite distinctive. Infected plants display white powder-like spots on the leaves and stems and specific russeting on fruits. The younger leaves are the most affected, but the mildew can appear on any part of the plant that shows above the ground. As the disease progresses, the spots get larger and thicker as massive numbers of spores form, and the mildew spreads up and down the length of the plant.
Powdery mildew species over-winter either as mycelium in dormant buds or as cleistothecia on plant tissues. When over-wintering as mycelium in dormant buds, in spring, the shoots arising from the contaminated buds at the end of the previous season become infected and provide inoculum (mycelium and spores) for the subsequent secondary infections and disease development on plant tissues.
It is known in the art that fluopyram shows a high level of efficacy especially against powdery mildew species on different crops. However, powdery mildew can overwinter in buds to produce early infections the year after (primary infected shoots).
Thus, there is a strong need for active ingredients which can be used to reduce the number of primarily infected shoots.